This invention relates to display devices in which one or more opaque back plates each having an array of openings therein are moved in an orbital path behind a face plate having an array of openings therein for each back plate, the openings in the face plate and back plates being positioned to coact to form indicia when light is transmitted through a predetermined selection of registering openings in the back plates and face plate. One example of such a display device is disclosed in U.S. Pat. No. 3,783,539 which discloses a digital clock.
In practice, the orbital drive mechanism for the back plates of the above described patent has been found to have a tendency to stick and thereby to stop the clock. The principal object of this invention is to provide an improved orbital drive mechanism which is not subject to sticking and which is more dependable.
Other objects, advantages and features of the invention will be apparent from the disclosure hereof.